1 files changed, 81 insertions, 0 deletions
diff --git a/arch/s390/include/asm/bitops.h b/arch/s390/include/asm/bitops.h
index 6f573890fb2..15422933c60 100644
--- a/arch/s390/include/asm/bitops.h
+++ b/arch/s390/include/asm/bitops.h
@@ -640,6 +640,87 @@ static inline unsigned long find_first_bit(const unsigned long * addr,
 }
 #define find_first_bit find_first_bit
 
+/*
+ * Big endian variant whichs starts bit counting from left using
+ * the flogr (find leftmost one) instruction.
+ */
+static inline unsigned long __flo_word(unsigned long nr, unsigned long val)
+{
+	register unsigned long bit asm("2") = val;
+	register unsigned long out asm("3");
+
+	asm volatile (
+		"	.insn	rre,0xb9830000,%[bit],%[bit]\n"
+		: [bit] "+d" (bit), [out] "=d" (out) : : "cc");
+	return nr + bit;
+}
+
+/*
+ * 64 bit special left bitops format:
+ * order in memory:
+ *    00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f
+ *    10 11 12 13 14 15 16 17 18 19 1a 1b 1c 1d 1e 1f
+ *    20 21 22 23 24 25 26 27 28 29 2a 2b 2c 2d 2e 2f
+ *    30 31 32 33 34 35 36 37 38 39 3a 3b 3c 3d 3e 3f
+ * after that follows the next long with bit numbers
+ *    40 41 42 43 44 45 46 47 48 49 4a 4b 4c 4d 4e 4f
+ *    50 51 52 53 54 55 56 57 58 59 5a 5b 5c 5d 5e 5f
+ *    60 61 62 63 64 65 66 67 68 69 6a 6b 6c 6d 6e 6f
+ *    70 71 72 73 74 75 76 77 78 79 7a 7b 7c 7d 7e 7f
+ * The reason for this bit ordering is the fact that
+ * the hardware sets bits in a bitmap starting at bit 0
+ * and we don't want to scan the bitmap from the 'wrong
+ * end'.
+ */
+static inline unsigned long find_first_bit_left(const unsigned long *addr,
+						unsigned long size)
+{
+	unsigned long bytes, bits;
+
+	if (!size)
+		return 0;
+	bytes = __ffs_word_loop(addr, size);
+	bits = __flo_word(bytes * 8, __load_ulong_be(addr, bytes));
+	return (bits < size) ? bits : size;
+}
+
+static inline int find_next_bit_left(const unsigned long *addr,
+				     unsigned long size,
+				     unsigned long offset)
+{
+	const unsigned long *p;
+	unsigned long bit, set;
+
+	if (offset >= size)
+		return size;
+	bit = offset & (__BITOPS_WORDSIZE - 1);
+	offset -= bit;
+	size -= offset;
+	p = addr + offset / __BITOPS_WORDSIZE;
+	if (bit) {
+		set = __flo_word(0, *p & (~0UL << bit));
+		if (set >= size)
+			return size + offset;
+		if (set < __BITOPS_WORDSIZE)
+			return set + offset;
+		offset += __BITOPS_WORDSIZE;
+		size -= __BITOPS_WORDSIZE;
+		p++;
+	}
+	return offset + find_first_bit_left(p, size);
+}
+
+#define for_each_set_bit_left(bit, addr, size)				\
+	for ((bit) = find_first_bit_left((addr), (size));		\
+	     (bit) < (size);						\
+	     (bit) = find_next_bit_left((addr), (size), (bit) + 1))
+
+/* same as for_each_set_bit() but use bit as value to start with */
+#define for_each_set_bit_left_cont(bit, addr, size)			\
+	for ((bit) = find_next_bit_left((addr), (size), (bit));		\
+	     (bit) < (size);						\
+	     (bit) = find_next_bit_left((addr), (size), (bit) + 1))
+
 /**
  * find_next_zero_bit - find the first zero bit in a memory region
  * @addr: The address to base the search on